The present invention relates to a circuit for protecting a microprocessor from noise. The invention is intended for use especially in association with a coin validator, as described for example in GB 2284090, the contents of which are incorporated herein by reference.
Noise in the form of unwanted electrical signals in a circuit arising from the environment can cause the circuit to malfunction. A known method of removing noise uses filters to filter out signals of particular frequencies. A problem with that approach is that the filters require large inductive and capacitive components, which increases the size and cost of the circuits.
The invention provides a circuit for protecting a microprocessor in a controller for a currency validator from noise comprising means for detecting noise and means for temporarily halting the microprocessor when noise is detected.
As a result of the invention, it is not necessary to provide bulky components for removing noise signals. The halting of the microprocessor can prevent adverse consequences of high frequency interference.
The invention also provides a controller for a coin validator comprising a circuit as described above.